The trend in the circuit protection industry is currently toward complete circuit protection which is accomplished by the addition of supplemental protection apparatus to standard overcurrent protective devices, such as molded case circuit breakers. In the past, when such auxiliary protection apparatus or other circuit breaker accessories were combined with a standard circuit breaker, the accessories were usually custom-installed at the point of manufacture. The combined protective device, when later installed in the field, could not be externally accessed for inspection, replacement or repair without destroying the integrity of the circuit breaker interior. U.S. Pat. No. 4,894,631 describes a molded case circuit breaker containing an actuator-accessory unit which provides a wide variety of circuit protection accessory options. This patent is incorporated herein for purposes of reference and should be reviewed for its description of the state-of-the-art of such circuit breakers and accessory devices.
U.S. Pat. No. 4,913,503 describes a reset mechanism for a lower ampere-rated circuit interrupter usually employed as a "branch" circuit interrupter within industrial power distribution systems downstream from a higher ampere-rated "main" circuit interrupter. When actuator-accessory units are used within the higher-rated circuits, the actuator-accessory units are incapable of providing sufficient force, per se, to overcome the holding force of the powerful operating mechanism springs. Additional tripping force is provided by a supplemental tripping mechanism which interacts with the actuator-accessory unit through a sequential resetting system to insure that the actuator-accessory unit becomes reset before the main operating mechanism is reset.
U.S. patent application (41PR-6785) describes a sequential resetting system that interfaces between the tripping mechanism and the actuator-accessory unit of a higher-rated molded case circuit interrupter to insure that the actuator-accessory unit becomes reset before the main operating mechanism. U.S. patent application (41PR-6800) describes the supplemental tripping mechanism that interacts with the actuator-accessory unit to provide sufficient tripping force to articulate the circuit interrupter operating mechanism. Additional accessory devices, such as the bell alarm described in U.S. patent application Ser. No. 311,794 filed Feb. 17, 1989, are often required with such circuit interrupters containing a sequential resetting system and a supplemental tripping mechanism. All three of these Applications are incorporated herein for purposes of reference. In order to use standard accessory designs over a wide range of circuit interrupter ampere ratings, some means must be provided to operate the accessory devices within both higher as well as lower-rated circuit interrupters.
One purpose of this invention accordingly, is to describe a bell alarm accessory arrangement whereby a prior bell alarm design for lower-rated circuit interrupters can also be used within higher-rated circuit interrupters.